On 19/12/2017 6:15 AM, Sarah Friedrich wrote:
Dear all,
the CRAN Package Check Results for my package GFD indicate an error on
windows (https://cran.r-project.org/web/checks/check_results_GFD.html),
which I am unable to fix. In my package, I'm using RGtk2 for creating a
GUI. Since this produced errors before, I first check if RGtk2 is
available via
requireNamespace("RGtk2", quietly = TRUE)
if(!("package:RGtk2" %in% search())){attachNamespace("RGtk2")}
That code doesn't quite make sense. Some background first:
A package can be "loaded" or "loaded and attached". If your DESCRIPTION
file has the package in the Imports list, it will be automatically
loaded. If it is in the Depends list, it will be automatically loaded
and attached. But if it is in the Suggests list, neither of these will
happen automatically.
If a package is loaded but not attached, then it will not be on the
search list.
You can load a package using requireNamespace(). Your first line of
code does that. If the package has already been loaded, nothing will
happen. You can load and attach it using require(). Both of these
functions return a logical value to indicate success.
You almost never need to call attachNamespace. If you really need to
have the package on the search list (and this is rare), you should have
called require(). Usually you just need code like this:
if (!requireNamespace("RGtk2", quietly = TRUE))
# Signal that RGtk2 is not available.
If the error didn't happen, then RGtk2 is now guaranteed to be loaded,
and you can call functions from it using code like
RGtk2::foo()
If you don't want to always use the prefix RGtk2::, then you could have
used require("RGtk2", quietly = TRUE) when you loaded it, but this is
frowned upon, because the user might not want RGtk2 in their search
list. (It might have functions with the same names as functions from
other packages, and that can mess up the user's code.)
Duncan Murdoch
It all works fine on linux (x86_64-suse-linux-gnu (64-bit)) and on R
version 3.2.5 on windows (x86_64-w64-mingw32/x64 (64-bit)), so I suspect
that it's not actually an error in my package but something between
RGtk2 and the new R version on windows. Anyway, a workaround would be
greatly appreciated! Do you have any suggestions?
Thanks a lot in advance and best regards,
Sarah
______________________________________________
R-package-devel@r-project.org mailing list
https://stat.ethz.ch/mailman/listinfo/r-package-devel
______________________________________________
R-package-devel@r-project.org mailing list
https://stat.ethz.ch/mailman/listinfo/r-package-devel
